Data classes for value holders in Kotlin - Mini Project: Build & Apply

Data classes for value holders

📖 Scenario: You are creating a simple app to store information about books in a library. Each book has a title, an author, and a year of publication.

🎯 Goal: Build a Kotlin program that uses a data class to hold book information, creates a list of books, and prints their details.

📋 What You'll Learn

Create a data class called Book with properties title, author, and year

Create a list called library containing three Book objects with exact values

Use a for loop with variables book to iterate over library

Print each book's details in the format: Title: [title], Author: [author], Year: [year]

💡 Why This Matters

🌍 Real World

Data classes help organize related information clearly, like storing book details in a library app.

💼 Career

Understanding data classes is essential for Kotlin developers to write clean, maintainable code that models real-world data.

1

Create the data class Book

Create a Kotlin data class called Book with three properties: title of type String, author of type String, and year of type Int.

Kotlin

// Your code here

Need a hint?

Use the data class keyword followed by the class name and properties inside parentheses.

2

Create a list of books called library

Create a list called library containing three Book objects with these exact values:
1. Title: "1984", Author: "George Orwell", Year: 1949
2. Title: "To Kill a Mockingbird", Author: "Harper Lee", Year: 1960
3. Title: "The Great Gatsby", Author: "F. Scott Fitzgerald", Year: 1925

Kotlin

data class Book(val title: String, val author: String, val year: Int)
// Your code here

Need a hint?

Use listOf() to create the list and call the Book constructor for each item.

3

Loop through library to access each book

Use a for loop with variable book to iterate over the library list.

Kotlin

data class Book(val title: String, val author: String, val year: Int)

val library = listOf(
    Book("1984", "George Orwell", 1949),
    Book("To Kill a Mockingbird", "Harper Lee", 1960),
    Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
)

// Your code here

Need a hint?

Use for (book in library) to loop through the list.

4

Print each book's details

Inside the for loop, write a println statement to print each book's details in this exact format:
Title: [title], Author: [author], Year: [year]
Use the book variable's properties.

Kotlin

data class Book(val title: String, val author: String, val year: Int)

val library = listOf(
    Book("1984", "George Orwell", 1949),
    Book("To Kill a Mockingbird", "Harper Lee", 1960),
    Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
)

for (book in library) {
    // Your code here
}

Need a hint?

Use println with string templates like "${book.title}" to insert values.